Fix annotation UA-1 checks

DEVSIX-8679

Author: vitali-pr

pdfua/src/main/java/com/itextpdf/pdfua/checkers/utils/AnnotationCheckUtil.java

@@ -126,8 +126,9 @@ public void processElement(IStructureNode elem) {
                 throw new PdfUAConformanceException(PdfUAExceptionMessageConstants.ANNOT_TRAP_NET_IS_NOT_PERMITTED);
             }
 
-            if (!PdfName.Widget.equals(subtype) && !(annotObj.containsKey(PdfName.Contents)
-                    || annotObj.containsKey(PdfName.Alt))) {
+            PdfStructElem parent = (PdfStructElem) objRef.getParent();
+            if (!PdfName.Widget.equals(subtype) &&
+                    !(annotObj.containsKey(PdfName.Contents) || (parent != null && parent.getAlt() != null))) {
                 throw new PdfUAConformanceException(MessageFormatUtil.format(
                         PdfUAExceptionMessageConstants.ANNOTATION_OF_TYPE_0_SHOULD_HAVE_CONTENTS_OR_ALT_KEY, subtype.getValue()));
             }

pdfua/src/main/java/com/itextpdf/pdfua/exceptions/PdfUAExceptionMessageConstants.java

@@ -101,8 +101,8 @@ public final class PdfUAExceptionMessageConstants {
             "in pdf encryption dictionary.";
     public static final String TENTH_BIT_OF_P_VALUE_IN_ENCRYPTION_SHOULD_BE_NON_ZERO = "10th bit of P value of " +
             "Encryption dictionary should be 1 if the document is tagged.";
-    public static final String ANNOTATION_OF_TYPE_0_SHOULD_HAVE_CONTENTS_OR_ALT_KEY = "Annotation of type {0} should " +
-            "have contents or alternate description.";
+    public static final String ANNOTATION_OF_TYPE_0_SHOULD_HAVE_CONTENTS_OR_ALT_KEY = "Annotation of type {0} shall " +
+            "have contents or alternate description (in the form of an Alt entry in the enclosing structure element).";
     public static final String LINK_ANNOTATION_SHOULD_HAVE_CONTENTS_KEY = "Annotation of type Link " +
             "shall contain an alternate description via their Contents key.";
     public static final String CT_OR_ALT_ENTRY_IS_MISSING_IN_MEDIA_CLIP = "CT or Alt entry is missing from the media " +